Alkyl and hydroxyalkyl nitro amines and process for preparing them



Patented Apr. 22, 1947 UNITED STATES PATENT DFFICE ALKYL AND HYDROXYALKYL, Nrrno' AMINES AND raocnss FOR ranraamG THEM Murray Senkus, Terre Haute, Ind. assignor to Commercial Solvents Corporation. Ten-e Hante, Ind., a corporation of Maryland No Drawing. pplication mm 2c,- 1945,

I Serial No. 579,894

My invention relates to new nitro amines and r to a process for the preparation thereof. Specifically, these new compounds may be represented by the following structural formula:

nitroisobutyl) -2-ethylhexylamine; 2 nitro 2 .methyl-l octadecylaminopropane; 2-nitro-1-dimethylamino-Z-methylpropane; 2-nitro l di methylamino-2-methylbutane; Z-nitro-l-dibutylamino-2-methyipropane; N-(2 nitroisobutyl) bis(2-ethylhexylamine) N-(2 nitroisobutyl) 2 amino-2-methyl-l-propainol; N- (2 nitroisobu tyl) -2-amino-1-butanol; N (2 nitroisobutyl) bis(2-hydroxyethylamiue) and the like.

This application is a continuation-in-part of my co-pending application, Serial No. 455,931 flied August 24, 1942.

Prior investigators in this field have found that primary nitroparaflins would react with N-(hydroxymethyl) dialkylamines; however, they also arrived at the conclusion, while making the aforesaid discovery, that N-(hydroxymethyl) monoalkylamines would not react with primary nitroparaiflns, and that secondary nitroparafiins would neither react with N-hydroxymethyl mono-nor dialkylamines under any of the experimental conditions which they had found to be effective in condensing a primary nitroparaflln with N-(hydroxymethyl) dialkylamines. Previous workers also were of the opinion, in view of their own experimental results, that neither primary nor secondary nitroparaflins would react with conden-- sation products derivable from formaldehyde and ammonia, formaldehyde and primary alkylamines, formaldehyde and aniline, formaldehyde and diphenylamine, formaldehyde and N-methylaniline, and numerous other products of similar structure prepared from higher molecular weight aldehydes and primary or secondary amines.

Contrary to that which would normally be expected in view of the above prior art findings,

however, I have discovered that nitro amines of the type described may be prepared by reacting formaldehyde with a primaryor secondary amine to form the corresponding N-(hydroxymethyl) mono-, or dialkyior di'nydroxyalkylamine, which is in turn reacted with an equimolecular amount of a secondary nitroparaflin to produce a nitro amine of the type represented by the generic formula given above.

A modification of the above procedure may frequently be employed to advantage, and consists of reacting the desired amine with a suitable nitro alcohol. A solvent may be used if desired, but in general it will be found that a homogeneous solution can be obtained by agitating the mixture of amine and nitro alcohol. The products, produced by this process are identical with those synthesized by the first mentioned method; however, the

' mechanism of the reaction in its initial stages is materially different from that involved in the first procedure. In this connection, it has been observed that primary nitro alcohols, when in the .presence of a substance appreciably basic in character, decompose into formaldehyde and the nitroparaflln from which theywere derived, and in instances where the basic material hap ns to be a primary or secondary amine, the liberated formaldehyde reacts therewith to form an N-(hydroxymethyl) amine compound which then reacts with the nitroparaiiln, produced by the decomposition of the nitro alcohol, in the same manner as described in the first procedure. The course of the reaction involved may be readily illustrated by the following series of equations.

v N-(hydroxymethyl) Nitroprlmary or secondparaflin --o Desired nitroamine ary amine From an examination of the above series of equations, it will be evident that although the starting materials are difierent from those used in the process first described, both procedures may be considered equivalents of one another, since the compounds employed as starting materials in the first process are produced as intermediates in the second, after which said intermediates react in a manner identical with the mechanism involved, in the reaction forming the basis of the first mentioned method; Therefore, it is to be specifically understood that the appended process claims include both methods.

The preparation of these nitro amines by either of the above-mentioned methods, is preferably efiected at temperatures of from about 25-30 C. Temperatures above this range may be used, but in doing so care should be exercised to avoid temperatures which cause the formaldehyde to be volatilized from the reaction mixture. In some cases it may be desirable to carry out the reaction in a highpressure reaction vessel. Under such circumstances, substantially higher temperatures may be utilized without loss of formaldehyde, and decomposition of the reactants, or the reaction products.

The amines which may be employed in preparing these new compositions of matter are represented by the formula:

wherein R may be either hydrogen, alkyl or hydroxyalkyl, and It may be alkyl or lwdroxyalkyl. As examples of such amines there may be mentioned ethylamine, butylamine, dimethylamine, methylamine, isopropylamine, l-methylheptylamine, 2 ethylhexylamine, 2 amino 2- methyl-l-propanol, 2-amino-1-butanol, dibutylamine, bis(2-ethylhexyl)amine, ethanolamine, diethanolamine, 2-amino-2-ethyl-1-propanol, 2- aminc-Z-methyl-l-hexanol, and the like.

Nitroparafiins that are operative in my process may be represented by the following formula:

wherein R and R represent alkyl radicals.

Nitroparafiins typical of this class are 2-nitropropane, Z-nitrobutane, z-nitropentane, and the like.

In the reaction wherein nitro alcohols are employed instead of a nitroparafi'in and formaldehyde, the following are examples of typical nitro alcohols which may be utilized: 2-nitro-2-methyl-l-propanol, 2-nitro-2-methyl-l-butanol, 2-nitro-2-ethyl-1-pentanol, 2-nitro-2-ethyl-1-buta- 1101, and the like.

The examples which follow are illustrative of the various types of nitro amines that come within the scope of the present invention. The examples are likewise illustrative of the procedures by which said products may be synthesized. It is to be specifically understood, however, that the following examples in no way limit the scope of my invention with respect to either the product or the process, since I have found that the reaction involved is very general in nature, and will occur, under the conditions described, when reacting substantially any secondary nitropar- 4 affin with a primary or secondary amine of the various types enumerated above.

EXAMPLE I One hundred and eighteen parts of isopropylamine was placed in a suitable 3-necked reaction vessel fitted with a condenser, a sealed stirrer, a dropping funnel, and a thermometer well reaching into the liquid. Sixty parts'of a 35 per cent aqueous formaldehyde solution was added slowly to the reaction vessel while the mixture was agitated. The temperature of the mixture was not allowed to exceed 25 C. during the period of the addition of the aldehyde. One hundred and seventy-eight parts of 2-nitropropane was then added to the reaction vessel, and the mixture stirred for 30 minutes without further cooling. Twenty parts of sodium sulfate was next added to the mixture, and stirring continued until the salt had dissolved. The nonaqueous layer was removed from the crude reaction mixture, and allowed to stand at room temperature, whereupon a small additional amount of water separated from the crude product. Fractional distillation of the product yielded 242 parts of substantially pure N-isopropyl-2-nitroisobutylamine, boiling at C. (10 mm.)

EXAMPLE II Fifty-nine parts of isopropylamine and 119 parts of 2-nitro-2-methyl-l-propanol were placed in a reaction vessel and hermetically sealed. This mixture was then stirred until it had become homogeneous, after which the resulti-ng solution was allowed to stand at room temperature. After approximately 10 hours, an aqueous lower layer appeared and when the separation of'the water had discontinued, the upper layer containing the crude nitro amine, was separated and distilled under reduced pressure. One hundred and sixty parts of N-isopropyl-2- nitroisobutylamine, boiling at 85 C. (10 mm.) was obtained in this manner, corresponding to a yield of 86 per cent.

EXAMPLE III To a mixture consisting of 218 parts of isopropylamine and 60 parts of a 35 per centaqueous formaldehyde solution, was added 206 parts of Z-nitrobutane, in accordance with the procedure described in Example I. After all of the 2- nltrobutane had been added, 30 parts of sodium sulfate was introduced, and the resulting mixture stirred until the salt dissolved. The crude product separated as an oil, and after being removed, was distilled and the portion, boiling at 95-9'7 C. (10 mm.) collected. The N-(2-nitro- 2 methylbutyl)isopropylamine, thus obtained amounted to a conversion of 90 per cent on the basis of the 2-nitrobutane used.

EXAIVIPLE IV Two moles of 2-amino-2-methyl-l-propanol were placed in a three-necked reaction flask fitted with a condenser, a sealed stirrer, a dropping funnel, and a thermometer reaching into the liquid. Two moles of 36% by weight aque- .ous formaldehyde were added slowly to the amine in the vessel while the mixture was agitated. The temperature of the mixture was sodium sulfate were then addedto the reaction mixture and stirring was continued until the salt had dissolved. Two liquid layers separated and the non-aqueous layer was separated from 16 EXAMPLE VI One mole of diethanolamine and one mole oi 2-nitro-2-methyl-1-propano1 were placed in a Method A utilizes amine, nitro araflln and formaldehyde.

Method B utilizes amine and the water layer. After standing for several days 5 s ass-stopp ed r action vessel and the mixture the mixture was filtered and the filtrate i'racwas shaken until it had become homogeneous.- tionated to yield 282 parts of N-(2-nitrolso- The solution was allowed to stand at room tembutyD-2-amino-2 methyl 1 propanol correperature. Water began to sep 8 a l r sponding to a conversion of 90%. Th nitrogen layer after about 10 hours and the separation of content found was 14.84% as compared to a cal- 10 water had ceased after about 3 days. Two liquid oulated value of 14.74%. The product was a soil layers rormed and were separated, N-(Z-nitroisohaving a melting point 01 59.0 C. butyl) -bis(2-hydroxymethylamine) being in the I top non-aqueous layer. The product was not EXAMPLE V purified as it decomposed on distillation. The crude product was hydrogenated and converted Two moles of z-amino-l-butanol were placed to N-(2- m1no]5obu'ty1)-bis(2 hydroxymethylinathree-necked reaction flask fitted withaconmine) in convegslon of 25% based on t denser, a sealed stirrer, a dropping f nn and starting nitroalcohpl. The nitrogen content a thermometer reaching into the liquid. Two found was 5. as compared to calculated moles of by weight equeeus formaldehyde value of 15.09%. The productboiled at 140 0. were added slowly to the amine in the vessel at 1 mm pressure and had an 20 of 838 and while the mixture was agitated. The temperature of the mixture was maintained at about m C. during the addition of the aldehyde. Two 20 moles of 2-nitropropane were added to the mix- 25 ture during agitation over a period of about 19338- mmutea Twenty grams of sodium ulfate were The tableappearing below gives additional exthen added to the reaction mixture and stirring mines of mt'mammes accm'dmg to was continued until the salt had dissolved. Two or other o the elternetwe methods described liquid layers separated and t non..aqueous 30 and listed. in the examples given above. The layer 'was separated from the water layer. After mtmamines indicated as having been Prepared standing for several days the mixture was filtered y method Were P p ed ythe method of Exand the filtrate fractionated to yield 38 parts of ample I utllizing an a n th a n roparafiln N-(Z-nitroisobutyl) -2-amino-1 butanol corred f rmaldehyde, whereas those indicated as spending to a conversion of 10%. Thenitrogen being prepared y MethOd B Were pr pared by content found was 14.49% as compared to a calthe method of Example II utilizing equimolecular culated value 01 14.74%. The product was a proportions of the indicated amine and nitrosolld having a melting point of 59.1" C. alcohol.

Tm: I

Preparation of M810 amines olthctypl N-CHa- R' Starting Materials NContent c M thod Product vlu' i i m P901 0810,! F 6 3 82753 3 no 4:: Amino Nitroparaflin Wm pemen't g'g Formaldehyde Methylamlne 2-Nitropropane.. 2-Nitro-2-1nethyl-1-math- 48 A 21.21 21.02 130-626).... 1.4368 1.0166

ylamino ropane. mpmpylamm 9 fl$g f g g 17.50 17.34 84.0(10) 1.4330 0.9035 l-Butylamlne -d0 2-Nit r o-l -butyag1ino 2 A 16.09 10.17 -407 (10)-- 1.4407 0.9584

1118 1'0 2-Buty1amina 1142-11 1120 sfimt nn- 12 4 10.09 15.95 00.0(10) 1.4384 0.9571

methyl ropylamine. lsopropylamine 2-Nitrobutano... Z-lgfigo-ggggfmho- 90 A 10.09 16.09 96-07(10)..." 1.4409 0.9625 l-Msthylhoptylamine 2-Nitropropane N-(2-nizroisobt 1tyh-l- 78 B 12.18 12.30 -112 (0.5).- 1.4465 0.9%16

methylbeptylamine. 2-Ethyihexylaminn n N- -1 1 1:m 1:: 1;t 1 -a 07 B 12.18 12.34 100-101 1)--- 1.4486 0.9281

9 Oetadacylnmine.... .--d0 Z-Nitio-ilfimthyl-bocta 90 B 11.07 11.39 84.4 decylamino to no. 2-An1ino-2-methyl-1-prodo. N-(2-nitro so utyl)'2- 90 A 14.74 14.84 59.0

panol. amino-Z-methyl-l-pro- 2-A1nino 1-butanol do N I itrOimbutyDQ-am- 1o .4 14.14 14.49 68.1

. ino-l-butanol. mmemylamm" gggrgg figggg Z; 19.18 10.05 05-66(10)"... 1.4330 0.9784 Do 2-Nitr0butane-.. 2-Nitro-1-d methylamino- 76 B 17.50 17.71 64(3) 1.4410 0.9772

. 2-methylbutane. mbumamm zNitmpmpam" jfgggggg gge g g 1218 12.38 (10) 1.4453 0. 9180 Bis(2-ethylhexyl) amine.-. d0 N-(2-nitroiso 1iutylg-bifl2 othylhexylamine 1 Data for picrate. Melting point.

anaaoe The nitroamines of my invention are in general either colorless liquids or white waxy solids. The low molecular weight nitroamines possess characteristic pungent odors whereas the high molecular weight nitroamines are relatively odorless. The nitroamines are soluble in ether, methanol and benzene but are insoluble in water.

Some of the nitroamines of my invention have been found to be useful as toxicants in insect sprays. They are likewise useful as intermediates in the preparation of numerous organic compounds. Other uses of these products will readily occur to those skilled in the art.

Having now described -my invention, what I claim is:

1. In a process for the preparation of. nitro amines or the formula wherein R and R represent alkyl groups.

2. In a process for the preparation of nitro amines of the formula N-CHrC-R' wherein R represents a member selected from the group consisting of hydrogen, alkyl and hydroxyalkyl, R. represents a member selected from the group consisting of alkyl and hydroxyalkyl, and R and R represent alkyl radicals, the step' which comprises mixing with formaldehyde at temperatures above about 25 C., an amine having the formula N-H K wherein It represents a member selected from the group consisting of hydrogen, alkyl and hydroxyalkyl and R represents a member selected from the group consisting of alkyl and hydroxyalkyl, and a nitroalkane of the formula wherein R and R represent alkyl groups.

wherein R represents a member selected from the group consisting of hydrogen, alkyl and hydroxyalkyl, R represents a member selected from the group consisting of alkyl and hydroxyalkyl, and R. and R represent alkyl radicals, the step which comprises mixing at temperatures above about 25 C. an amine having the formula wherein R represents a member selected from the group consisting of hydrogen, alkyl and hydroxyalkyl and R represents a, member selected from the group consisting of alkyl and hydroxyalkyl,

and a nitroalcohol of the formula N02 H0 CHP-R wherein R and R represent alkyl groups.

4. A process for the preparation of N-isopropyl-2-nitro-isobutylamine, which comprises mixing isopropylamine with formaldehyde, and thereafter mixing the resulting product with 2- l nitropropane.

5. A process for the preparation of N-(2-nitro- Z-methylbutyl)isopropylamine, which comprises mixing isopropylamine with formaldehyde, and thereafter mixing the resulting product with 2- nitrobutane. a

- 6. In a process for preparing N-(Z-nitroisobutyl) -2-amino-2-methyl-'1-propanol, the step which comprises mixing 2-a-mino-2-methyl-1- propanol, formaldehyde and 2-nitropropane.

7. Nitro amines having the following structural formula wherein R represents a member selected from the group consisting of hydrogen, alkyl and hydroxyalkyl, R represents a member selected from the group consisting of alkyl andhydroxyalkyl, and R and R represent alkyl radicals.

8. N-isopropyl-2-nitroisobutylamine.

9. N-(2-nitro-2-methylbutyl) isopropylamine.

l0. N-(2-nitroisobutyl) 2 amino-2-methyll-propanol.

MURRAY SENKUS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES De Mauny, Bull. Soc. Chim. de France (5), 4

(Copy in Patent Oflice Library.)

Certificate of Correction Patent No. 2,419,506. 7 April 22, 1947.

MURRAY SENKUS It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Column 6, lines 22, 23 and 24, for

dgfi read dfiyand that the said Letters patent should be read with this correction therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 29th day of July, A. D. 1947.

LESLIE FRAZER,

First Assistant Commissioner of Patents. 

